1. Technical Field
The present invention relates to a package, an electronic device including the package, an electronic apparatus, a moving object, and a method of manufacturing an electronic device.
2. Related Art
In recent years, in various communication devices, and particularly, in mobile communication devices, there has been a strong demand for reduction in size for an electronic device. As electronic devices used in the mobile communication devices, there are a piezoelectric resonator, a piezoelectric oscillator, a piezoelectric sensor, a SAW filter, and the like.
In the piezoelectric devices whose size reduction is demanded as mentioned above, a configuration in which an element is sealed in a package formed of, for example, ceramics or the like to obtain stable properties have been known. As a specific example, a base member containing ceramics as a main material is used, an electron element is mounted in an opening portion of the base member, and a metal lid is joined by welding and the like so as to form an airtight space having high reliability in the opening portion.
FIGS. 7A and 7B are cross-sectional views showing a schematic configuration of a package structure disclosed in JP-A-2005-142329. FIG. 7A is a cross-sectional view before a lid is joined and FIG. 7B is an enlarged cross-sectional view of a main part after the lid is joined.
As shown in FIG. 7A, the package structure disclosed in JP-A-2005-142329 is configured such that a ceramic base 601 in which a metalized layer 602 is formed in an outer peripheral portion, and a lid 603 which is formed of two layers of a metal plate 603a and a brazing material 603b are airtightly sealed by joining the metalized layer 602 and the brazing material 603b by welding and the like.
In the structure, the lid 603 is formed of two layers of the metal plate 603a and the brazing material 603b as described above and has a bank portion 603C in which a part of the metal plate 603a protrudes toward the brazing material 603b at an outer peripheral end. Then, the brazing material 603b is prevented from being ejected to the outside from an interface portion between the metalized layer 602 and the metal plate 603a by joining the ceramic base 601 and the lid 603 by melting the brazing material 603b in a state in which a surface of the lid 603 on which the brazing material 603b is formed and the metalized layer 602 are in contact, and thus, deterioration in airtightness is prevented.
However, in the package structure disclosed in JP-A-2005-142329, although it is possible to prevent the brazing material 603b from being ejected at the interface portion between the metalized layer 602 and the metal plate 603a, the bank portion 603c is provided in which the outer peripheral portion of the metal plate 603a which forms the lid 603 protrudes toward the brazing material 603b. Thus, the brazing material 603b is not likely to flow out in the outer peripheral portion of the metal plate 603a. Therefore, as shown in FIG. 7B, the brazing material 603b in which the ceramic base 601 and the lid 603 are joined is in a state in which a fillet 604 is not likely to be formed over the metalized layer 602 and the entire outer peripheral portion of the metal plate 603a. 
In the package structure disclosed in JP-A-2005-142329, since a joining width (a seal pass 605) in which the metalized layer 602 of the ceramic base 601 and the brazing material 603b of the lid 603 are melted to be joined becomes narrow, there is a problem in that when the brazing material 603b is melted less, airtightness is deteriorated.
Furthermore, in the package structure disclosed in JP-A-2005-142329, since the fillet 604 of the brazing material 603b is not likely to be formed over the entire outer peripheral portion of the metal plate 603a, it is difficult to confirm a sealing state in an external inspection. Thus, there is a concern that the quality of an electronic device may not be maintained since it is very difficult to determine whether or not the sealing state is satisfactory in the package structure disclosed in JP-A-2005-142329.